function getdt()
%
% put the DT into the empty commentary fields.
%
global CONTROL

tc = strmatch('timing_cond', {CONTROL.protocol}, 'exact');
if(isempty(tc))
   return;
end;

for i = 1:length(tc)
   s = CONTROL(tc(i)).Commentary;
   epd = CONTROL(tc(i)).EPSPKdt;
   if(~isempty(epd) & isempty(findstr(s, 'dt=')))
      dt = epd.spkl-epd.shkl;
      fprintf(1, 'i: %d, dt=%6.2f\n', tc(i), dt);
      s = CONTROL(tc(i)).Commentary;
      CONTROL(tc(i)).Commentary = sprintf('%s  dt=%6.2f', s, dt);
   end;
end;
datac('setlist'); % force list update